Field of the Invention
The present invention relates to methods and apparatuses for providing a link model for a multi-prefix packet system bearer, e.g. an evolved packet system bearer.
Related Background Art
The following meanings for the abbreviations used in this specification apply:    3GPP Bearer=a dedicated point to point connection for a UE    3GPP=third generation partnership project    ANDSF=access network discovery and selection function    API=application programming interface    APN=access point name    DSMIPv6=dual stack mobile IPv6    eNB=evolved nodeB    EPS=evolved packet system    GGSN=gateway GPRS support node    GPRS=general packet radio service    GRE=generic routing encapsulation    GTP=GPRS tunneling protocol    HeNB=home eNodeB    IAP=internet access point    IPv6=internet protocol version 6    ISP=internet service provider    L1=Layer 1=physical layer    Link=interface at link layer (layer 2)    L-GW=local gateway    LIPA=local IP access    MAPCON=multi access PDN connectivity    MME=mobility management entity    NIC=network interface connection at physical layer    OPIIS=operator policies for IP interface selection    OS=operating system    PDN=packet data network    PDP=packet data protocol    PGW=P-GW=packet data gateway    PMIPv6=proxy mobile IPv6    PPP=point to point protocol    RA=routing advertisement    RAT=radio access technology    SGW=S-GW=serving gateway    SIPTO=selected IP traffic offload    UE=user equipment    ULA=unique local address    USB=universal serial bus
3GPP Rel-8 has introduced dual-stack for EPS, and 3GPP Rel-9 has supported dual-stack correspondingly for GPRS bearers. That is, PDN/PDP type has been extended to IPv4v6, i.e., both IPv4 and IPv6 addresses are available to a UE.
Based on agreed IP addressing principle, exactly one IPv4 address and exactly one IPv6 prefix can be assigned to the UE (excluding link scoped prefix) per a PDN connection/PDP context.
New features beyond 3GPP Rel-9 like LIPA, SIPTO, MAPCON, OPIIS and equivalent mechanisms have shown that there is a need for more IPv6 prefixes per bearer, for example to have a separate prefix for user traffic “offloading” purposes.
The current 3GPP bearer model is proprietary and tailored for 3GPP terminals by assuming that end-users will use mobile operator provided packet switched services.
However, smart phones are coming into the market that use ordinary internet services, and their operating systems implement their IP stack and network interfaces at link layer according to generic IP networking principles. Thus, interworking between applications using socket based IP stack in a smart phone OS and a 3G modem using bearers is quite complex.
A proprietary 3GPP bearer model that is limited to one IPv6 prefix per PDN is becoming problematic especially when IPv6 will be applied in larger scale.
IPv6 is by design a multi-addressed and -prefix architecture, in which an interface must have a link scoped prefix and then may have zero or more prefixes of wider scope (ULAs, globals, . . . ). ISPs with complex content & service provisioning structure and access infrastructure sharing settlements make use thereof.
The 3GPP bearer model comprises an “old” point-to-point link model used since GPRS, in which the link is between a UE and a PGW/GGSN, and a “new” point-to-point link model used with PMIPv6, in which the link is between a UE and an SGW but an IPv6 prefix/IPv4 address is still topologically anchored to a PGW.
Since GPRS times 3GPP compliant host OSes have abstracted a PDP connection as a dial-up “PPP-like” interface. Modern host OSes wish to abstract everything as IEEE802 type interface. This results in not working combinations due to false assumptions made at both end host and network side regarding link model and addressing.
A 3GPP solution for multiple prefixes is to establish a new default bearer (PDN connection) each time a new prefix is needed in the UE. However, this causes unnecessary overhead.
According to patent application US 2011/110378 A1 “Method And Apparatus For Communications Traffic Breakout”, published on May 12, 2011, more than one address per PDN connection/PDP context is used in order to offload local breakout traffic in a “middle-box” on the data path by using source address lookup (IP address, Ethernet address, or the like).
According to these applications, the current 3GPP bearer model is changed to support multiple addresses per PDN connection.